Thank you all for the advice. Given that it seems impossible to transfer warranties to new owners, I'm extra glad that I decided to not keep the Nikon myself, since I would have never been able to sell it at a future point in time.

Any Nikon camera can be (and many of them are) sold at any time. It's just that once it had one owner, the next one cannot have the manufacturer's warranty. Once this period expires, there is no disadvantage in selling a used product. In this case this period is 12 months.

I like being able to sell gadgets I own, in case something that suits me better comes along. This warranty issue will be a deal breaker for any Nikon products I would have considered in the future.

If this is a deal breaker for you, then you will hardly ever be able to by any gadgets of any brand as most manufacturers have the same policy.